带果肉芹菜汁的流变特性研究

研究了带果肉芹菜汁的流变特性,发现带果肉芹菜汁的表观粘度随浓度的增大而增大;随温度的升高而减小;在72～314μm的范围内,随果肉颗粒粒度的减小而减小。     

浑浊胡萝卜汁的流变特性研究

通过对不同温度不同浓度不同颗粒大小下的带肉胡萝卜汁进行研究,初步探索出浓度、温度及肉泥颗粒大小对胡萝卜汁表观粘度的影响。发现带肉胡萝卜汁的粘度随浓度的增大而增大;随温度升高而下降;内含平均粒度为111μm,133μm和166μm的果肉的胡萝卜汁的粘度比含其它粒度的大。     

超细大豆豆皮膳食纤维部分物理性质的研究

超细粉碎后的大豆豆皮膳食纤维的吸水量、吸水速率随粒度的减小而减小;可溶性物质随温度升高而增多,随粒度减小而增多;黏度随着溶液浓度的升高而升高,随着粒度的减小而减小.超细粉碎后大豆豆皮膳食纤维的混合颗粒吸水量最大、吸水速率最高,可溶性物质最少,而黏度最大.     

重质碳酸钙稳定的O/W型Pickering乳液及其粒度效应研究

以重质碳酸钙作为颗粒稳定剂制备O/W型Pickering乳液,利用球磨法获得不同尺寸的碳酸钙,研究碳酸钙颗粒粒度、颗粒浓度、油相比例对乳液类型、稳定性、微观形貌及流变学特性的影响。结果表明:球磨后不同粒度的碳酸钙均能稳定Pickering乳液,且该乳液具有一定的储存稳定性,固体颗粒粒径对乳液性质有一定的影响,乳液粒径随固体颗粒粒径的增大而增大;随固体颗粒浓度的增大,乳液的乳析指数、乳液粒径以及乳液黏度均减小,但当固体颗粒浓度达到9g/100 mL以上时,增加颗粒浓度对乳液粒径影响不大;增大油相比例会使乳析指数减小、乳液粒径和黏度增大。     

脚板薯淀粉的发酵法制备及其淀粉糊流变特性研究

采用发酵法制备脚板薯淀粉,分析了其淀粉颗粒粒度、淀粉糊透明度及凝沉性等理化性质,并对淀粉质量浓度、糊化pH、温度、不同介质及其浓度对淀粉糊流变特性的影响进行了分析。结果表明:脚板薯淀粉得率为15.2%,纯度为97.6%;淀粉平均粒度为18291.5nm,淀粉糊透光率为27.92%,其凝沉时间短;淀粉糊黏度随着淀粉浓度的增加而增加,随着糊化温度的增加而减小;在酸性条件下,淀粉糊黏度随着糊化pH增加而减小,pH到达8时,黏度达最大值,后随碱性的增强淀粉糊黏度下降。加入食盐、氯化钙和蔗糖均可提高淀粉糊的黏度,且在相同的剪切速率下,淀粉糊黏度随着蔗糖添加量的增大而增大。     

淀粉溶液的通电加热研究

本文研究了食盐浓度、淀粉浓度和电压对淀粉溶液的电导率和通电加热速率的影响;研究了通电加热对淀粉糊化特性的影响。结果表明:淀粉溶液在通电加热过程中,加热速率和电导率随食盐浓度的增大而增大;随电压的升高而增大;随淀粉浓度的增大而减小。而电导率在达到糊化温度之前随温度的升高而增大,在糊化温度之后随温度的升高而降低。淀粉溶液在通电加热时其糊化特性无明显变化。     

不同粒度密本南瓜粉的物化特性及抗氧化性

比较4个不同粒度范围的密本南瓜粉的物化特性及抗氧化性,结果表明:随着粒度的减小,蛋白质、脂肪含量增多,总氨基酸含量在16.58~17.12 mg/g之间;总糖和还原糖含量呈先增加后减小的趋势;Fe、Zn、Mn含量随粒度减小而减少;容重、持水力、膨胀力都随粒度减小而逐渐减小,吸潮性、亮度、黄度随粒度减小而增大;总酚含量随粒度的减小而减小,β-胡萝卜素含量随粒度减小而增大。对1,1-二苯基-2-三硝苯肼自由基的清除能力随静置时间的延长而增强,100~200目的南瓜干粉静置1 h后的清除率达到94.94%;100~200目密本南瓜干粉对超氧阴离子的清除能力最强,达到37.62%。     

带肉胡萝卜汁的流变特性研究

本文研究了不同温度、浓度和不同均质压力处理的带肉胡萝卜汁的流变特性，发现带肉胡萝卜汁的表观粘度随果肉浓度的增大而增大：随温度的升高而减小；而随着均质压力的增大则出现先增大后减小的规律。     

管束式除雾器除雾特性数值模拟

采用计算流体力学(CFD)对管束式除雾器内部流场进行数值计算,分析除雾效率及压力损失随叶片倾角、颗粒粒径、烟气流速等参数的变化规律。结果表明:除雾效率随颗粒粒径及烟气流速的增大而增加,随叶片倾角的增大而减小;压力损失随烟气流速的增大而增加,随叶片倾角的增大而减小;叶片倾角15°的管束压力损失过大,不符合实际应用;叶片倾角60°的管束适合作为前级粗除雾,控制进入后级除雾器的颗粒浓度;叶片倾角30°的管束适合作为后级精除雾,控制吸收塔的颗粒排放总量。     

胞壁蛋白酶（CEP）酶解对酪蛋白结构及功能特性的影响

通过纳米粒度分析、傅立叶红外光谱（FTIR）、乳化性、乳化稳定性、蛋白溶解性、抗氧化性及ACE抑制率的测定,分析探讨酪蛋白及其不同水解度（DH 2.4%、4.5%、7.1%、8.3%）的嗜酸乳杆菌胞壁蛋白酶（CEP）酶解产物的结构及功能特性。FTIR分析表明CEP酶解改变了酪蛋白各种构象所占的比例,酪蛋白二级结构发生了不同程度的变化;纳米粒度分析表明酪蛋白颗粒大小随水解的加深先减小后增大,其水解物颗粒在DH 4.5%时最小,乳化稳定性最大;酪蛋白的乳化性随水解的加深先增大后减小,DH 7.1%时增至最大,与其溶解性的变化趋势一致;此外酪蛋白的酶解物具有一定的ACE抑制活性及抗氧化性,且DPPH清除能力在一定范围内随水解度及浓度的增大而增大,当DH为8.3%,浓度为5mg/mL时,DPPH清除能力增大至35.00%。因此CEP酶解可有效改善酪蛋白的结构及功能特性,为乳源性功能多肽的开发提供理论依据。     

炭黑色浆对干法腈纶原液性能的影响

研究了干法腈纶纺丝原液中炭黑色浆的加入对原液的流动性、孔口胀大效应及色度等的影响，结果表明，随炭黑加入量的增加体系的表观粘度下降、孔口胀大效应变小、原液的粘度对温度的敏感性下降、原液的色度增加，但同时也降低了纤维的物理机械性能?     

果胶酶对甘薯浆流变学行为的影响

采用中心组合设计和响应面分析法研究不同处理时间(16～134min)、处理温度(20～70℃)和加酶量(0.005%～0.105%,m/m)下果胶酶对甘薯浆流变学行为(屈服应力、流动性特征指数、黏稠系数)和表观黏度的影响。结果表明：未经果胶酶处理和经过果胶酶处理的甘薯浆均为非牛顿性流体、呈现假塑性同时具有屈服应力。Herschel-Bulkley 模型可以较好的拟合剪切应力和剪切速率的相关性;研究发现,果胶酶处理使甘薯浆的非牛顿性流体流变行为减弱,同时其表观黏度随着果胶酶浓度的增加而逐渐降低。经过果胶酶处理后的甘薯浆的表观黏度最小值为71.56mPa·s,对应的酶浓度为0.1%,酶处理时间为70.56min,酶处理温度42.34℃。     

Viscoamylographic Studies on Zea Mays [Mexican White Tuxpeño Maize] Partial Gelatinization with Calcium Hydroxide

Mexicans staple food is maize “tortilla”, prepared by thermal‐alkaline processes. The sensory properties of “masa” and “tortilla” depend on the reactions occuring between lime and chemical compounds in maize. In the present study, the effect of different calcium hydroxide, Ca(OH)₂, concentrations (0.0, 0.10, 0.30, 0.50 %, dry basis, d.b.) on the apparent viscosity and maximum gelatinization temperature of a cornstarch water slurry was assessed. This Mexican traditional thermal‐alkaline gelatinization reaction (TAGR) was evaluated in a Brabender Viscoamylograph. This small well‐mixed reactor was homogeneously heated, and apparent viscosity data from corn starch were recorded in Brabender Units BU). It was found that an increase in Ca(OH)₂ concentrations considerably increases the apparent viscosity, thus reducing the time needed to reach the maximum gelatinization temperature. A mathematical model that represents the phenomena, that occur in the Viscoamylograph, was developed. In the model the Viscoamylograph was considered as a batch reactor and the apparent kinetic coefficients for the TAGR were obtained, including mass balances and thermal‐alkaline gelatinization rates, considering a spherical cornstarch granule formed by a starchy matrix. Activation energy found for this reaction was 1241 kJ.     

Changes in viscosity and pectolytic enzymes of tomato and strawberry juices processed by high-intensity pulsed electric fields

The effects pulse frequency (50–250 Hz), pulse width (1.0–7.0 μs) and polarity (monopolar or bipolar) of high-intensity pulsed electric field treatments (35 kV cm⁻¹ and 1000 μs) on viscosity and the pectin methylesterase (PME) and polygalacturonase (PG) activities were evaluated using a response surface methodology. Second-order expressions were accurate enough to fit experimental results. Tomato juice apparent viscosity increased within the range of the assayed conditions, achieving the highest values at 250 Hz and 7.0 μs in bipolar mode. At the same conditions the lowest residual PME (RA_PME = 10%) and PG (RA_PG = 45%) activities were observed in the juice. Apparent viscosity of strawberry juices slightly rose when frequencies higher than 100 Hz and 1-μs monopolar pulses were applied to the juice. Treatments causing the greatest increase in strawberry juice apparent viscosity also led to the lowest RA_PME (10%) and RA_PG (75%) values. In contrast, viscosity loss was promoted under the rest of assayed HIPEF conditions despite the low RA_PME values (<20%) achieved. Moreover, RA_PG did not decrease below 75% throughout the range of studied conditions.     

Effect of sodium caseinate on the stability of cream liqueurs

The apparent viscosity of cream liqueurs prepared with different commercial sodium caseinates increased on storage at 45°C at rates and to extents that were dependent on which caseinate was used in the cream liqueur preparation. Increases in the apparent viscosity of fat free and fat free, micellar casein and whey protein free liqueurs indicated that differences in the caseinate s per se, rather than differences in interfacial absorption of the caseinates or the inclusion of micellar casein and whey proteins with the cream serum, caused the differences in increases in the apparent viscosity of cream liqueurs on storage at 45°C. No significant correlation was found between the calcium content of the caseinates and increases in the apparent viscosity of the liqueur systems on storage at 45°C. Addition of 2-mercaptoethanol to liqueurs after manufacture caused large increases in apparent viscosity, indicating that sulphydryl interactions may be important. Addition of NaCl to cream liqueurs resulted in an immediate increase in apparent viscosity, and on storage at 45°C for seven days, the liqueurs gelled, developed a high apparent viscosity or underwent phase separation, depending on which caseinate was used in the manufacture of the cream liqueur. Thus changes in the apparent viscosity of cream liqueurs on storage at 45°C are caseinate dependent and the results presented suggest that electrostatic and sulphydryl interactions may be involved in these changes.     

易染色聚酯熔体的流变性能

采用高压毛细管流变仪研究了易染色超仿棉聚酯熔体的流变行为,并将其与聚酯熔体的流变行为进行了对比。结果表明：易染色聚酯熔体属于典型的假塑性非牛顿流体,表现出明显的剪切变稀特性;随着温度的升高,易染色聚酯熔体的表观黏度下降,非牛顿指数逐渐增大,结构黏度指数减小;易染色聚酯熔体的黏流活化能随着剪切速率的增大而减小,即其表观黏度的温度敏感性随着剪切速率的增大而降低;与PET熔体相比,易染色聚酯熔体的表观黏度对温度和剪切速率的依赖性更高,且结构化程度更大。     

Functionality of strawberry powder on frozen dairy desserts

This study investigated the potential use of freeze‐dried strawberry powder as a stabilizer in frozen dairy desserts. Five different dessert mixes were developed that contained 0%, 2.5%, 3%, 3.5%, and 4% strawberry powder. An additional dessert using strawberry extract was prepared to differentiate the effects of dietary fiber from the effect of polyphenols on sample properties. The rheological and physical characteristics of dessert mixes, fresh dessert, and stored dessert were studied. The addition of strawberry powder to dairy desserts caused an increase in the mix viscosity and a decrease in hardness and meltdown values. Complete avoidance of meltdown was achieved with the addition of 3% or greater amount of strawberry powder. The viscosity of mixes was enhanced due to the increase of total solids in the serum phase and the formation of hydrated and gel‐like networks in the presence of cellulosic material, pectin, and calcium. The increase in viscosity and unfrozen water with the addition of strawberry powder also caused a reduction in ice crystallization, which resulted in softer and more stable desserts over time.     

Effects of addition of strawberry juice pre- or postfermentation on physiochemical and sensory properties of fermented goat milk

Fruit juice addition can influence the physiochemical and sensory properties of fermented milk. Effects of adding strawberry juice (15% vol/vol) pre- or postfermentation on particle size, rheology properties, volatile flavor profile, and microstructure of fermented goat milk were investigated. Samples with juice added prefermentation showed larger reinforcement in particle size, apparent viscosity, and storage and loss moduli than samples with juice added postfermentation. Compared with the control, all samples showed improved fruit aroma and reduced goaty flavor; this effect was more remarkable in samples in which juice was added before fermentation. Fermented goat milk with strawberry juice added prefermentation showed the highest levels of 1-hexanol and 2-hexen-1-ol (26.16 and 22.03%, respectively) and the lowest percentage of octanoic acid (2.47%), which are mainly responsible for fruit and goaty flavor, respectively. Microstructure analysis showed that samples with juice added prefermentation had a compact protein network. Results indicated that addition of strawberry juice before fermentation may be a good technology for developing a stirred strawberry fermented goat milk.     

树枝状聚合物对轻质碳酸钙加填纸张性能的影响

在轻质碳酸钙研磨时,加入1%的自制树枝状聚合物进行改性,结果表明:对轻质碳酸钙悬浮液的分散起到很好的作用,其黏度下降50%以上;作为造纸填料使用时,其加填纸张的抗张强度、耐破度、撕裂强度都有显著提高。     

Xylanases in Wheat Separation

Hemicellulases used in the wheat separation process have resulted in better separation, purer fractions, increased plant capacity, reduced processing time etc. In order to further improve enzyme-treatment in the wheat separation process, monocomponent xylanases were evaluated. A laboratory viscosity model has been set up to evaluate the xylanases. The model showed good correlation (for a commercial hemicellulase preparation used for wheat separation) between viscosity of the wheat flour slurry and the sludge/supernatant ratio after centrifugation of the slurry. A xylanase (Novozyme 867) with excellent performance in the wheat separation process has been found. The xylanase has high activity towards soluble arabinoxylan and gives a rapid viscosity reduction of wheat flour slurries. The enzyme also has a moderate activity towards insoluble arabinoxylan, but due to the low molecular weight of the solubilized material this was not was found to contribute negatively to the enzymes' performance. The pH and temperature conditions in the wheat separation process were well within the active range of the enzyme. A pilot plant experiment showed improved yield of gluten and A-starch, with no apparent negative effect on the gluten quality.